Bireme & Galley covers naval combat from ancient times up until just before ships started mounting cannon. The game's subtitle is "Naval Warfare, Egypt to Lepanto."
The 99-page rulebook includes 31 pages describing the various kinds of warships in common use in ancient and medieval times (with many drawings) and 12 pages of ship data tables. The remainder of the rulebook consists of the actual rules, notes on some historical naval campaigns, and a section on using the game with FGU's Chivalry & Sorcery RPG.
While the game was designed for miniatures, 4 sheets of cut-apart ship counters were provided as a substitute. The game also included a ship record sheet (to be copied), a large sheet of deck plans (for man-to-man combat once ships grapple), and a turning template.